Custom ESC firmware with fixed max RPM for pylon racing

Hi Speedfreaks,

I am looking for a custom ESC firmware that could be used for pylon racing. We would like to get more equal racing by fixing RPM and prop size. That eliminates the benefit of buying the best batteries and buying fresh ones or each event. It will create a much more equal playing field for all contestants without costing too much money.
The reason i am looking for custom firmware instead of buying very expensive of the shelf ESC's that can be programmed on a PC is for 2 reasons: 1- Cost and 2-we would like something a little bit more tamper proof.

Do you know if something like this is already available? If not, I am looking for someone who could adapt existing custom firmware for multirotors for our specific needs as that seems the easiest way to go.

I raced in a class of racing that was simply limited by using a small esc as the limiter. For example we used a Castle Creations Thunderbird-18 esc. This limited peple to a maximum amount of watts the esc would take and pushing it beyond that was the risk of failure.

What airframes will you be using? Unless your lipos are huge it's probably easier to decide on a specific brand and KV of motor and then a prop that everyone has to use.... a good pilot with 30 or 40C lipos will beat an average pilot with 60 or 70C lipos....

Iím not a speed freak, but Iíve taken to AMA EF1 racing recently. From what Iíve seen, most pilots arenít that critical about their batteries Ė Iíve seen some pretty rough-looking packs used by some of the fastest guys in the district Ė with pretty ďuglyĒ connectors too. Iím probably a little more particular than most about my batteries and connectors, and Iím just a mid-pack guy most of the time. From what I see, I just donít have the feeling guys are running out to buy the latest, greatest battery or buying new ones all the time. And prop size is already fixed (APC 8 x 8 thin electric).

I guess Iím correlating my experience in AMA EF1 to whatever kind of racing youíre talking about, but the way it is now, it doesnít seem to be a money race for the latest technology and in the end, simply the best pilots who fly the course tight, smooth and consistent with properly set up planes (and a good caller!) are usually the ones who win.

Anyway, if you fix RPM and prop size, there will probably be some other variable that can be tampered with instead.

I guess I havenít answered your question but rejected the premise. Sorry about that. In the end, it seems like the average Joe understands the spirit of the rules, abides them and just goes out and competes and has fun whether or not he wins. Then there will always be the couple of guys who are driven to push the rules to the limit (Iím not talking about cheating) and us ďaverage JoesĒ can either continue to enjoy the competition anyway, or quit.

I am an EF-1 racer myself, but this question is more for the Dutch group of E2K pilots that I will be joining next season. E2K is very cheap to race. Simple airframes but with very fierce competition. The last 2 seasons we are seeing large speed differences between the guys with the brand new LiPo's and well built planes and the average Joe's as you call them. We want to prevent this from becoming a LiPo war so limiting RPM and prop is a very simple way to do that.

There has been some testing already with YEP controllers, but setting the govener max RPM on those is not easy. The CC ESC's are easy but too expensive for the class. We would hate to make all participants buy one of those. To give an idea of how cheap E2K is I have a list of the major components:
Airframe, 2 kits available at around $ 60,-
Motors are cheap Turnigy 1400Kv outrunners of ~$ 15,-
3 Mini servo's
60-80 amp ESC $ 35,-
2200 4S LiPo $ 30,-
Speed of these things is around 200 Km/h so a lot faster than EF-1

They are hand launched at the start, 3 simultaneously. That makes for very exciting racing!

Did you happen to check in with the control-line guys? See are using some clever electronics (external to the controller) to keep rpm constant if I'm not mistaken. There is a thread on the Dutch forum on this, might be possible to use this for pylon too?

Which YEP did you try, what rpmp are you looking for?
Remember running at part throttle heats the motor and ESC more than full throttle.
Gerben, maybe you could supply them with a YEP already programmed to do the job? Then they would not have to program it and couldn't change the max rpm?

George, we are testing the YEP 80Amp and are aiming for 15.000 to 16.000rpm.

Gerben, nice of you to chime in. I checked the line control solution, but that needs a lot of change to work for us. It has no receiver input and acts as PPM source for a normal ESC.

I would like to keep the setup as simple as possible every link you add to the chain adds points of failure.

I have the hardware to flash atmel chips so all we need is a HEX where we can set a fixed RPM. From the top of my head the motors we use are 14 pole outrunners. Without govener we run 8x6 props, with govener we would like to switch to 8x8 to be able to get to the same speed and have a little headroom for the govener to work with.

Gerben, you flew my YEP (same as the YGE) software in Austria. It works on the YEP 45, the YEP 150 from you, and the YGE200FAI. So I presume it will work on the YEP 80. I could remove the soft start software used on the YGE though it does nothing on the YEP.

I think I can add the rpm limiting easily as it similar to the ramping, but I would have to try. It would be for 14 pole motors only, though the code could be changed for other pole configurations by changing build parameters.

I am running out of time this year, very few programming days left before Christmas due to other engagements, but I will do what I can.

What kind of tools would we need to make changes to your software? Once the program is working there is probably some tuning of parameters to do. If we can do that ourselves that would save you a lot of time.

Here is a first attempt. I can't do any more until next week, so this will give you a chance to check the YEP 80 and the downloading system.
Remember, first tests using a current limited supply in case of short circuits.
Then keep checking the temperature of the FETs.
In my test this code has trouble starting and stopping, interaction between the throttle ramp and rpm limiter I think. But when it is running it seems to limit the rpm to just under 15000.

Very short of time between now and Christmas so if you can try as much as possible and give me feedback right away.

I use Atmel Studio 6.1 and an AVRISP for development. Code written in C with assembler macros.

ps Tjarko: this code is for 14 pole motor, don't use 10 pole. Different code required.